The decision by Popovich to end his run as coach of the San Antonio Spurs — it was announced by the team on Friday, along with the promotion of Mitch Johnson to the job — means that the longest active tenure by any coach in any of the four U.S. major pro sports had ended.

It's the end of an era in San Antonio as head coach Gregg Popovich steps down from the role after 29 seasons leading the Spurs. While this is a seismic development in the NBA, it also has ramifications that bleed into the NFL as well.

Pittsburgh Steelers head coach Mike Tomlin holds an exclusive status following Gregg Popovich's departure from Spurs.